I'm interested in teaching, sort of as the flip side to learning, so this page describes some projects along those lines. This is some combination of blog, manifesto, and reference material. There are four Teaching icons at the top of my home page. Currently only this page and the Main Sequence page are in active development.a

Table of Contents
Personal approach to teaching
Electric motors
The Teaching Agenda
Project references

Approach to Teaching
I have been doing freelance science teaching since about 2000, not counting some years of occasional science fair mentoring prior. My basic plan in teaching science is to spend time with students talking about what they are interested in or curious about.  Engaging student interest is the first priority and the basis of conversation. If I can connect their interest to some idea that I find interesting then great, we have a confluence of frames of mind. For example, if a student is interested in black holes I might talk about our sun, obviously not a black hole but a connected subject. The typical one-sentence description of a black hole highlights its strange characteristics, but this description also tends to act as a confinement of ideas; so let's move away from that and back up to a black hole precursor, then see how we get there from here. The discussion might eventually connect the sun and the students' direct experience of it to black holes which we observe indirectly. It is not easy to talk about something beyond direct experience so building bridges from the familiar is an extremely useful approach, and so the conversation might progress.

Other influences: If the student is obliged to take a Standardized Test or pass a course, that is, if the student is trying to meet an external requirement, this may drive conversational subject matter. If more than one student is involved we try to discuss ideas that are of interest to everyone. Sometimes it is a simple matter to find a starting basis for these conversations but most of the time it requires some work.

Searching for that starting point of the conversation, "finding where the rubber meets the road", is an abstraction, a way of thinking about learning and teaching in conversation. In my experience finding that starting point must happen before progress down that road is possible, else one person is merely talking at another.

I would like to expand on this by giving an extended example of finding such a starting point. I have two motivations for doing so. First I am trying to demonstrate the typical back-and-forth maneuvering necessary to find the very edge of the student's world view. Second I would like to illustrate the idea of 'closure on a premise'. By this I mean: Suppose I introduce a new idea or premise to the student and then make use of it to carry on the conversation. This can feel like nailing boards end to end in order to bridge a chasm, a tricky proposition. Wouldn't it be nice, then, upon reaching the other side of the chasm, to find oneself not in a strange new place but back on familiar territory? The bridge then connects to the student's experience twice, creating a type of closure. New ideas have not one but two anchor points, and in my experience (to mix metaphors) it is much easier to hold onto a loop than onto a dangling rope.

After this example I'd like to emphasize the teaching agenda, goals to try and reach while the conversation is in motion.

The Electric Motor Lesson
Suppose I have in mind building a little electric motor with a student. This is a very easy thing to do and it packs in a lot of basic ideas into something that moves, so it's a valuable type of lesson that combines concepts, physical construction, and in the end produces a very dynamic result.

Some people can build an electric motor with a student without mentioning electrons but I can not. I have to talk about electrons because without that idea I feel that the notion of electric current is unsupported. However I can not talk to a student about electrons unless they know what electrons are, in some sense. If they think an electron is a very small baseball that can be pushed around by mysterious forces (not gravity) then we're ok, that's enough, we can get started. If they do not have this picture or something like it for the electron then my thought is: Let's find a good starting point so we can work our way to the tiny baseball picture.

The student probably understands that something called electricity is necessary to make a lamp work, so I would be tempted to  start from that point. However I need more than just a retrograde postulate from electric current to electric particle since this is an unsupportable supporting another unsupportable. I need an external source of concepts to "build" the electron, and there are two readily available, one conceptual and one physical.

Suppose that conceptually the student has been taught that stuff is made from atoms. Fine; I can make the unsupported claim that atoms have constituent parts. This is where the rubber meets the road. We can build an atomic model in which electrons can be scraped away, and then we can produce a comb and scrape some electrons out of our hair and use them to pick up scraps of paper. We can also use the comb to deflect a thin stream of water falling out of the tap, and by the end of this we hope so far so good: There is a plausible argument for electrostatic force and electrons as small baseballs. (I would also not resist the temptation to hint that there is more to be found down this road, some more mysterious aspects of electrons call it mystery M.)

The next step is to differentiate insulators and conductors. Here the lamp concept pays off because we know the rubber that prevents us getting shocked is called insulation. I will have a little light bulb on the table that we can light by connecting it to a battery. Great! Producing light and heat is easy enough, and so now we can proceed to building a coil for our electric motor. Build for awhile, then put a voltage across the coil and notice that it produces a repulsion in a permanent magnet held nearby. Surprise: Making electrons travel in circles produces a magnetic field. Disconnect the battery, no more magnetic field.

Now a digression: Can we make magnets stronger by stacking them together? The answer is yes. Establish this with some ceramic magnets. So suppose we have a coil in a box, powered by a tiny watch battery. Without knowing what's inside we can hold a magnet nearby and feel the magnetic field emanating from it. In fact suppose we have many such coil-boxes. Let's imagine we stack these together in a bundle, then will the result be a stronger magnet? Yes, we imagine so because stacking magnets produces a stronger magnet.

Now imagine that we can make many many coil-boxes, each with its own electrons and its own battery to make it go, each of a very very small size. I would emphasize to the student that we are building an interesting picture, simply thinking about coil boxes that produce magnetic fields without having to actually build them. We can do this because we have built a single coil and played around with it. Let's stack a lot of small coil-boxes together to create a magnet that is indistinguishable from a ceramic magnet; they both produce a magnetic field and you can attach other magnets to them and so on. Ok, big deal, we have a strong magnet made from a bunch of little coil-boxes each containing a battery and a coil with electrons going in circles inside.

Here is the $17 question: What should we call the little coil-boxes? Yes we could call them little coil-boxes but let's come up with a better name. At this point maybe the student will guess the better name, and if not we can at least enjoy coming up with cool names for the invention.

Of course the 'better name' is atom. An atom is a coil-box. This is the second connection, the anchor point back to the student's existing picture. We start off talking about atoms and stripping away electrons, then we push those electrons through coils, then we notice the coils produce magnetic fields, then we notice that permanent magnets can reinforce one another, and finally we imagine little coil-boxes that stack together to make permanent magnets, and this is exactly what permanent magnets are so that coil boxes are really just atoms... but if everything is made of atoms and atoms are little magnets then why are some things magnets and other things not??? and where the heck are the little batteries???

There is another deeper problem with this explanation that I need to allude to in passing. Paramagnetism is a consequence of electron spin, not a classical current loop or Bohr orbits or orbital angular momentum. The problem is that spin is an intrinsic characteristic of electrons and not in any sense some sort of whirling distribution of charge. Spin is the place where quantum mechanics stops even pretending to be a slightly weird version of classical electromagnetism. So in a sense this complex 'coil box' picture breaks down still further and one of two things will happen (at least!) Either the flow of the discussion will be adequately satisfying that we can move on and leave deeper matters for another day. Or we will be faced with a dissatisfied student who senses the incomplete nature of the presentation. This has to be ok (and I suspect why we have evolved a sense of humour.) 

At this point we can run current through the coil and notice that it is getting hot... so perhaps it is plausible that the energy in the battery is just going into heating the coil and the magnetic field is not a type of energy expenditure or loss. Again these conversations might blow up and get very open-ended. In all events we're heading onto thin ice, let's face it. In fact anywhere along the way I'm quite prepared to say "I don't know. Beats me. Maybe the answer is tied up in Mystery M..." Because somewhere in here we're going to hit a point where the model and my understanding reach their limits. But then we can finish the motor and make it run, so working in my favor is at least the physical evidence that there is something screwy going on here and it definitely involves electricity and magnetism. I will hope for the best, that something useful comes out of the experience for the student. Of course when they hit my explanation wall I am motivated to go learn it better as well.

One final philosophical note: It can be immensely satisfying to explain something plausibly to a student. But like burning newspaper it can be fun and entertaining for a few minutes while failing to get any sort of lasting fire burning. Therefore conversational teaching is only a starting tool, a way to get things moving. I mention this because I think it is important to not mistake conversational teaching for successful teaching, which by definition has important lasting beneficial effect.

The Teaching Agenda
I believe that the foregoing conversation example and others like it act on students primarily through indirect influence. They can show that matters are complex and interesting, a perspective that is beneficial to adopt. So a considerable amount of the teaching I do is really just modeling enthusiasm, interest and excitement. This is part A of my teaching agenda. There are two parts total and they are equally important.

Part B is reflecting enthusiasm back at the student. If they ask a question or offer an answer, my immediate thought is 'How can I reflect their participation back on them so that they see themselves as bright and capable?' There are a lot of ways to do this but I think they are all based on listening carefully to what the student offers. This also means being willing to completely alter course in order to accommodate their ideas.

Project Links
The following links describe various past, present, and future projects in more detail.

• Rainy-night Astronomy.
  

• Tutoring

• Science Fair Mentoring

• The Einstein Centennial (with NOVA)

• Lectures on Geophysics, Planetary Science, and Astronomy
• Origins of the Moon
• Standard Candles
• Fun Jobs in the Arctic
• Space Aliens Among Us
• The Utility of Blind Optimism and Boundless Enthusiasm
  

• The CU Boulder Physics Education Program

• Matters in the public forum